Ask any seasoned writer what is the most important aspect of a story after the plot. She would answer 'the character'. Why?
Before I answer the question, let's take you as an example. After leaving the cinema or turning of the TV set, what will you talk about? What would you kids or little brothers and sisters talk about? The colour of the cartoons? Or the storyline? I'm sure you'd agree with me when I say that you'd end up talking about the characters, if not the cast. Kid's will remember the Red Ranger from the Power Rangers. After watching a thriller/suspense flick, you'd remember the anaconda, the bees, the spiders and even the crocodile. Harry Potter fans would beg to differ - they'd remember Daniel Radcliffe. ;-)
Characters move the story. The storyline is dull without characters. How can you understand a scenario when you cannot experience it yourself? Or at least have no reference point to relate to?
The question which any screenwriter - pro or amateur, new or veteran - needs to answer is 'how to create compelling characters?'
One way I can share with you now is by asking the market. So, dear friend, what would you like to see in a character? What are their weaknesses and their strength? What traits do they have?

